Joining Composite Components Using Low Temperature Thermoplastic Film Fusion

Abstract

Composite components are joined together by an amorphous thermoplastic film forming a fused thermoplastic joint between the components. Fusion of the film may be achieved at relatively low temperatures that are sufficient to cure thermoset composite components, but are below the melting point of semi-crystalline thermoplastic components.

1 . A method of joining two thermoplastic components comprising:
 producing a first thermoplastic composite component by placing a first amorphous thermoplastic film on a first stack of thermoplastic pre-preg, and co-consolidating the first amorphous thermoplastic film and the first stack of thermoplastic pre-preg;   producing a second thermoplastic composite component by placing a second amorphous thermoplastic film on a second stack of thermoplastic pre-preg, and co-consolidating the second amorphous thermoplastic film and the second stack of thermoplastic pre-preg;   assembling the first and second thermoplastic composite components, including placing the first and second amorphous thermoplastic films against each other;   pressing the first and second amorphous thermoplastic films against each other by applying pressure to the first and second thermoplastic composite components; and   fusing the first and second amorphous thermoplastic films together at a temperature below approximately 475° F.   
     
     
         2 . The method of  claim 1 , wherein producing the first thermoplastic composite component includes:
 placing the first amorphous thermoplastic film against a joining surface of the first stack of thermoplastic pre-preg, and   co-consolidating the first amorphous thermoplastic film and the first stack of thermoplastic pre-preg includes heating the first stack of thermoplastic pre-preg to the melt temperature of the pre-preg in the first stack thereof and compressing the first stack of thermoplastic pre-preg with the first amorphous thermoplastic film.   
     
     
         3 . The method of  claim 1 , wherein co-consolidating the second amorphous thermoplastic film and the second stack of thermoplastic pre-preg includes:
 heating the second amorphous thermoplastic film to its glass transition temperature,   heating the second thermoplastic pre-preg to its melt temperature, and   compressing the second stack of thermoplastic pre-preg with the second amorphous thermoplastic film.   
     
     
         4 . The method of  claim 2 , wherein heating the first stack of thermoplastic pre-preg to its melt temperature includes heating the first stack of thermoplastic pre-preg to a temperature greater than approximately 650° F. 
     
     
         5 . The method of  claim 1 , wherein:
 each of the first and second thermoplastic pre-preg is a semi-crystalline, and   each of the first and second amorphous thermoplastic films is PES.   
     
     
         6 . The method of  claim 1 , wherein each of the first and second thermoplastic pre-preg is one of PEEK, PEKK and PPS. 
     
     
         7 . The method of  claim 1 , wherein each of the first and second amorphous thermoplastic films has a thickness between approximately  5  mm and  7  mm. 
     
     
         8 . An integrated thermoplastic structure having thermoplastic components joined by the method of  claim 1 . 
     
     
         9 . A method of joining a thermoplastic composite component with a thermoset composite component, comprising:
 forming a first composite component by co-consolidating an amorphous thermoplastic film with a stack of semi-crystalline thermoplastic pre-preg;   forming a second composite component including a stack of thermoset pre-preg;   assembling the first and second components, including placing the amorphous thermoplastic film against the stack of thermoset pre-preg; and   curing the stack of thermoset pre-preg.   
     
     
         10 . The method of  claim 9 , wherein:
 co-consolidating the amorphous thermoplastic film with the stack of semi-crystalline thermoplastic pre-preg includes—
 placing the amorphous thermoplastic film against a joining surface on the stack of semi-crystalline thermoplastic pre-preg, 
 heating the stack of semi-crystalline thermoplastic pre-preg to its melt temperature, 
 heating the amorphous thermoplastic film to its glass transition temperature, and 
 compressing the amorphous thermoplastic film and the stack of semi-crystalline thermoplastic pre-preg, and 
   curing the stack of thermoset pre-preg includes heating the stack of thermoset pre-preg to a temperature sufficient to cure the thermoplastic pre-preg.   
     
     
         11 . The method of  claim 9 , wherein curing the stack of thermoset pre-preg is performed by thermal curing at a temperature less than approximately 400° F. 
     
     
         12 . The method of  claim 9 , including fusing the amorphous thermoplastic film with the stack of thermoset pre-preg at a cure temperature of the thermoset pre-preg. 
     
     
         13 . The method of  claim 9 , wherein the amorphous thermoplastic film is PES. 
     
     
         14 . The method of  claim 9 , further comprising:
 compressing together the amorphous thermoplastic film and a stack of semi-crystalline thermoplastic pre-preg.   
     
     
         15 . The method of  claim 9 , further comprising:
 placing an amorphous thermoplastic film on the stack of thermoset pre-preg, and   wherein assembling the first and second components includes placing the amorphous thermoplastic film on the first composite component against amorphous thermoplastic film on the stack of thermoset pre-preg.   
     
     
         16 . The method of  claim 9 , wherein:
 the amorphous thermoplastic film is PES, and   the thermoset pre-preg is a polyaryletherketone.   
     
     
         17 . The method of  claim 9 , wherein heating the stack of semi-crystalline thermoplastic pre-preg to its melt temperature includes heating the stack of semi-crystalline thermoplastic pre-preg to a temperature of at least approximately 650° F. 
     
     
         18 . A composite structure produced by the joining method of  claim 9 . 
     
     
         19 . A method of adhering a thermoplastic composite component to a non-thermoplastic component, comprising:
 co-consolidating an amorphous thermoplastic film with a stack of semi-crystalline thermoplastic pre-preg;   forming an assembly by assembling the co-consolidated amorphous thermoplastic film and stack of thermoplastic pre-preg with a non-thermoplastic component, including placing the amorphous thermoplastic film against the non-thermoplastic component;   applying pressure to the assembly to force the amorphous thermoplastic film against the non-thermoplastic component; and   fusing the amorphous thermoplastic film to the non-thermoplastic component.   
     
     
         20 . The method of  claim 19 , wherein the fusing is performed by heating the amorphous thermoplastic film to a temperature below approximately 475° F. 
     
     
         21 . The method of  claim 19 , wherein the co-consolidating is performed by:
 heating the amorphous thermoplastic film and the stack of semi-crystalline thermoplastic pre-preg to at least the melt temperature of the semi-crystalline thermoplastic pre-preg, and   compressing together the amorphous thermoplastic film and the stack of semi-crystalline thermoplastic pre-preg.   
     
     
         22 . The method of  claim 19 , wherein the amorphous thermoplastic film is PES. 
     
     
         23 . The method of  claim 19 , wherein the non-thermoplastic component is one of:
 a thermoset composite,   a metal, and   a ceramic.   
     
     
         24 . A method of joining two thermoset composite components, comprising:
 forming a first stack of thermoset pre-preg;   forming a second stack of thermoset pre-preg;   placing a thermoplastic film between the first and second stacks of thermoset pre-preg; and   consolidating together and thermally co-curing the first and second stacks of thermoset pre-preg with the thermoplastic film.   
     
     
         25 . The method of  claim 24 , wherein the thermoplastic film is amorphous and becomes glassy at a cure temperature of the first and second stacks of thermoset pre-preg. 
     
     
         26 . The method of  claim 24 , wherein the thermoplastic film is PES. 
     
     
         27 . The method of  claim 24 , wherein the thermal co-curing is performed by heating the first and second stacks of thermoset pre-preg and the thermoplastic film to a temperature less than approximately 500° F. 
     
     
         28 . A composite structure having two thermoset composite components joined by the method of  claim 24 . 
     
     
         29 . A composite structure having improved impact resistance, comprising:
 first and second co-cured thermoset composite laminates; and   a layer of thermoplastic between the co-cured thermoset composite laminates.   
     
     
         30 . A composite structure, comprising:
 a thermoplastic composite laminate;   a thermoset composite laminate; and   an amorphous thermoplastic film layer joining the thermoplastic composite laminate with the thermoset composite laminate.   
     
     
         31 . A method of joining a first thermoplastic composite component to a second thermoplastic composite component, comprising:
 co-consolidating a first amorphous thermoplastic film and a first fiber-reinforced semi-crystalline thermoplastic polymer matrix composite structure at a first temperature exceeding approximately 650° F. and a first pressure equal to or greater than approximately 100 psi to form the first thermoplastic composite component including a first amorphous thermoplastic polymer-rich surface;   co-consolidating a second amorphous thermoplastic film and a second fiber-reinforced semi-crystalline thermoplastic polymer matrix composite structure at a second temperature exceeding approximately 650° F. and a second pressure equal to or greater than approximately 100 psi to form the second thermoplastic composite component including a second amorphous thermoplastic polymer-rich surface;   mating the first amorphous thermoplastic polymer-rich surface of the first thermoplastic composite component and the second amorphous thermoplastic polymer-rich surface of the second thermoplastic composite component; and   heating, at a temperature between approximately 450° F., and 500° F. and compressing together, at a pressure between approximately 14.7 and 150 psi, the first thermoplastic composite component and the second thermoplastic composite component for a period of time sufficient to bond the first amorphous thermoplastic polymer-rich surface and the second amorphous thermoplastic polymer-rich surface without damaging the first thermoplastic composite component and the second thermoplastic composite component.   
     
     
         32 . The method of  claim 31 , wherein the step of heating, at a temperature between approximately 450° F. and 500° F., and compressing together, at a pressure between approximately 14.7 and 150 psi, the first thermoplastic composite component and the second thermoplastic composite component is performed in an autoclave oven. 
     
     
         33 . The method of  claim 31 , wherein the step of heating, at a temperature between approximately 450° F. and 500° F., and compressing together, at a pressure between approximately 14.7 and 150 psi, the first thermoplastic composite component and the second thermoplastic composite component is performed using an oven and a vacuum bag. 
     
     
         34 . The method of  claim 31 , wherein the step of heating, at a temperature between approximately 460° F. and 500° F., and mutually biasing, at a pressure between approximately 14.7 and 150 psi, the first thermoplastic composite component and the second thermoplastic composite component is performed using an oven and mechanical pressure. 
     
     
         35 . A method of joining a thermoplastic composite component to an uncured thermoset composite component, the method comprising:
 co-consolidating an amorphous thermoplastic film and a fiber-reinforced semi-crystalline thermoplastic polymer matrix composite structure at a temperature exceeding approximately 500° F. and a pressure equal to or greater than approximately  100  psi to form a thermoplastic composite component having an amorphous thermoplastic polymer-rich surface;   mating the amorphous thermoplastic polymer-rich surface of the thermoplastic composite component and the uncured thermoset composite component; and   heating, at a temperature of approximately 350° F., and mutually biasing, at a pressure equal to or less than 100 psi, the thermoplastic composite component and the uncured thermoset composite component for a period of time sufficient to cure the uncured thermoset composite component and to bond the amorphous thermoplastic polymer-rich surface thereto without damaging the thermoplastic composite component.   
     
     
         36 . The method of  claim 35 , wherein the uncured thermoset composite component includes a thermoset epoxy matrix and the amorphous thermoplastic film is compatible therewith.